Pass the CompTIA Linux+ XK0-005 Questions and answers with CertsForce

The cause of the issue based on the output above is C. The inodes is at full capacity and would affect file creation for users.

An inode is a data structure that stores information about a file or directory, such as its name, size, permissions, owner, timestamps, and location on the disk. Each file or directory has a unique inode number that identifies it. The number of inodes on a filesystem is fixed when the filesystem is created, and it determines how many files and directories can be created on that filesystem. If the inodes are exhausted, no new files or directories can be created, even if there is enough disk space available.

The output for the second command shows that the /ftpusers/ filesystem has 0% of inodes available, which means that all the inodes have been used up. This would prevent users from creating new files on the FTP server. The administrator should either delete some unused files or directories to free up some inodes, or resize the filesystem to increase the number of inodes.

The other options are incorrect because:

A. The users do not have the correct permissions to create files on the FTP server.

This is not true, because the output for the first command shows that the /ftpusers/ filesystem has 26% of disk space available, which means that there is enough space for users to create files. The permissions of the files and directories are not shown in the output, but they are not relevant to the issue of inode exhaustion.

B. The ftpusers filesystem does not have enough space.

This is not true, because the output for the first command shows that the /ftpusers/ filesystem has 26% of disk space available, which means that there is enough space for users to create files. The issue is not related to disk space, but to inode capacity.

D. ftpusers is mounted as read only.

This is not true, because the output for the first command does not show any indication that the /ftpusers/ filesystem is mounted as read only. If it was, it would have an (ro) flag next to the mounted on column. A read only filesystem would prevent users from creating or modifying files on the FTP server, but it would not affect the inode usage.

loginctl is a systemd utility that allows querying and controlling of login sessions. The command loginctl list-sessions displays a list of sessions currently logged into the system, including session IDs and user names. This is the official method to determine active logins in a systemd environment.

Source: man loginctl

To examine runtime configuration, including ENTRYPOINT and CMD, the docker inspect command is used.

A is correct: docker inspect provides detailed JSON-formatted output with ENTRYPOINT, command, volumes, environment variables, etc.

Incorrect Options:

B: Invalid command.

C: Shows running containers and basic status, not configuration.

D: Displays logs, not config parameters.

The git pull command fetches changes from the remote repository and merges them into the current branch. This is the correct command for obtaining the updated configuration that was pushed to the remote repository.

The error message no mutual signature algorithm indicates that the RSA key used is not compatible with the server’s SSH configuration — often due to deprecated RSA algorithms (e.g., RSA with SHA-1). Newer OpenSSH versions disable weak algorithms by default, requiring clients to use a modern key algorithm such as ECDSA or Ed25519.

Option A is ineffective; restarting the SSH service will not change the available algorithms.

Option C is irrelevant as it addresses root login, not user admin.

Option D is a good practice but doesn’t resolve algorithm mismatches.

Therefore, the administrator should generate a new key with a supported algorithm, such as ECDSA:

bash

ssh-keygen -t ecdsa

This is supported by CompTIA Linux+ XK0-005 Study Guide under:

Domain 3.0: Security – “Secure Shell (SSH) Configuration”

"OpenSSH may reject older RSA keys due to disabled SHA-1 signatures. Keys using ECDSA or Ed25519 are recommended for compatibility and stronger security."

The su command is used to switch to another user account on Linux systems. The - option makes the shell a login shell, which means that it will read the profile and environment variables of the target user. Without this option, the shell will retain the environment variables of the original user. This can cause confusion when issuing commands that depend on these variables, such as ls, which uses the $HOME variable to determine the home directory. Therefore, Ann should have issued su - Joe to list Joe’s files instead of her own. References: [How to Use su Command in Linux with Examples]

chgrp finance q1/: changes group ownership to finance.

chmod g+s q1/: enables setgid bit, so new files inherit the group.

Tab 1: List of logins on Mar 13

Best Command:

grep "Mar 13" log.txt

Reasoning:

This command searches for lines in log.txt containing "Mar 13", which matches the date shown in the output. The result shows all login records for that day.

Tab 2: List of logins on Mar 12 (UPPERCASE) including REBOOT entries

Best Command:

awk '{ print toupper($0) }' log.txt

Reasoning:

All lines in the output are in UPPERCASE, including the word "REBOOT". This command converts every character in each line to uppercase, which matches the output format exactly.

Tab 3: List of unique usernames (sorted) including 'reboot'

Best Command:

awk '{ print $1 }' log.txt | sort | uniq

Reasoning:

This command extracts the first column (the username), sorts them, and removes duplicates, resulting in a list of unique usernames in alphabetical order. The output matches exactly.

 Tab 1 shows logins for "Mon Mar 13" –> grep "Mar 13" log.txt

 Tab 2 shows all entries in uppercase (including "REBOOT") for "Sun Mar 12" –> awk '{ print toupper($0) }' log.txt

 Tab 3 shows unique usernames in sorted order –> awk '{ print $1 }' log.txt | sort | uniq

 grep "Mar 13" log.txt

Searches for and displays all log entries from March 13.

 awk '{ print toupper($0) }' log.txt

Prints each line from log.txt in all uppercase letters (including system reboots).

 awk '{ print $1 }' log.txt | sort | uniq

Extracts just the username from each log entry, sorts them, and removes duplicates for a clean list.

The best command sequence to rebuild a kernel module from source code is A. ./configure make make install. This is the standard way to compile and install a Linux kernel module, as explained in the web search result 5. The other commands are either not relevant, not valid, or not sufficient for this task. For example:

B. wget gcc cp will try to download, compile, and copy a file, but it does not specify the source code, the module name, or the destination directory.

C. tar xvzf build cp will try to extract, build, and copy a compressed file, but it does not specify the file name, the module name, or the destination directory.

D. build install configure will try to run three commands that are not defined or recognized by the Linux shell.

For repairing XFS filesystems, the appropriate command is xfs_repair. Since the /opt/finapp directory resides on an XFS filesystem (indicated in the mount output), xfs_repair is suitable for diagnosing and fixing corruption in XFS inodes and extent trees. Using fdisk or fsck.ext4 is not appropriate for XFS filesystems, as these commands are intended for partitioning and ext4 filesystems, respectively. Reference: CompTIA Linux+ Study Guide.